Pasha set off for an undisclosed location yesterday and it is believed that his visit is linked to the fallout of Monday's US raid that resulted in the killing of bin Laden in a compound located a short distance from the Pakistan Military Academy in the garrison city of Abbottabad, sources told PTI.

The influential Dawn newspaper had reported that Pasha had gone to Washington on a "critical mission for putting an end to misgivings about Pakistan in the US" but the sources said the ISI chief had not gone to the US.

Some reports said Pasha may have travelled to a friendly country like China or Saudi Arabia but this could not immediately be confirmed.

An official statement issued on Thursday after a meeting of Corps Commanders chaired by army chief Gen Ashfaq Parvez Kayani said the military admitted its "own shortcomings in developing intelligence on the presence of Osama bin Laden in Pakistan".

It added that "an investigation has been ordered into the circumstances that led to this situation".

The Daily Beast, a website affiliated to Newsweek magazine, reported yesterday that the ISI chief "may step down, as the government looks for a fall guy for the bin Laden debacle".

It said Pasha's resignation "was only a matter of time".There were also uncorroborated reports that Pasha met the CIA's station chief in Islamabad before going abroad and reminded him of the ISI's contributions in the war on terror and the lead about bin Laden's courier that eventually led the US to the al Qaeda chief.

Though the Corps Commanders meeting on Thursday tried to address public doubts about the military's capabilities, analysts and observers have said that there are numerous unanswered questions regarding bin Laden's presence in Abbottabad, just 120 km from Islamabad, and the US raid.

Though US officials have said they do not have any evidence which proves that the top brass of the Pakistani military and intelligence were aware of bin Laden's presence in the country, they have put the onus on Pakistan to prove its innocence.

"Pakistan is now being asked to do something that could prove its sincerity and commitment to the fight against militancy," the Dawn reported.

While addressing a news briefing on bin Laden's killing on Thursday, Foreign Secretary Salman Bashir said reports about the ISI and elements in the government being in cahoots with al Qaeda were "a false hypothesis".

The report about the ISI chief's possible resignation has struck a chord with the Pakistani public, who feel they have been let down by the army and intelligence agency because of their failure to detect the presence of the world's most wanted man and their lack of knowledge of the US raid.

A message widely circulated in Pakistan on SMS and Twitter over the past two days reflected the anger and indignation of the people.

It read: "For sale! Obsolete army radar, can't detect copters, but can receive signals of Star Plus. Only Rs 999".